Based on Xinzheng, Jinxi and Fengyichang projects on the Jialing river, we studied the maximum navigable discharge of navigation -power junction on the middle reaches of Jialing river by the hydraulic model test and ship-model test. The channel navigation grading of the middle reaches of Jialing river is class Ⅳ, so the flood frequency of the maximum navigable discharge is 33.3% , but the Jialing river is a mountainous river, the flood frequency of the maximum navigable discharge is less than 10%. Model test results indicate that the maximum navigable discharge of Xinzheng, Jinxi and Fengyichang are 8 000 m3/s respectively,which may serve as a reference for the operation of the navigation-power junction.